1. Field
The field relates generally to an anisotropic conductive film, and more particularly, to an anisotropic conductive film for mounting an integrated circuit (IC) chip thereon and a display device having the same.
2. Description of the Related Technology
A display device is a device for displaying images, and recently, an organic light emitting diode (OLED) display has received much attention.
The OLED display has self-emission characteristics, so, unlike a liquid crystal display (LCD), the OLED display can be formed to be thinner and lighter without the necessity of a light source. In addition, the OLED has high quality characteristics such as low power consumption, high luminance, and a high response speed.
The OLED display can be manufactured by forming elements on a substrate made of glass or plastic, and integrated circuit (IC) chips for generating various signals to operate the display device may be mounted on a certain region of the substrate forming the display device. In this case, the display device may be classified as a chip-on-glass (COG) type, a chip on flexible printed circuit board (FPCB) (COF) type, and the like, depending on the substrate. Here, the COG refers to mounting the IC chips on the substrate, and the COF refers to mounting the IC chips on a film such as polyimide and the like.
In the case of the COG with the IC chips mounted on the substrate, an anisotropic conductive film (ACF) is interposed between a pad formed on the substrate and a terminal of the IC chip. In this case, a direct connection between the pad of the substrate and the terminal of the IC chip is made by conductive balls included in the ACF, and attachment between the substrate and the IC chip is made by an adhesive layer that is included in the ACF and covers the conductive balls. The conductive balls, which are compressed between the pad of the substrate and the terminal of the IC chip, have good power of restitution. Consequently, the contact area between the pad and the terminal increase according to pressure between the pad and the terminal. Accordingly, contact resistance between the conductive balls and the pad and that between the conductive balls and the terminal are lowered as the pressure applied to the conductive balls increases.
In this respect, however, if pressure of more than a certain level is applied to the conductive balls, the power of restitution of the compressed conductive balls would exceed the fixing capability limit of the adhesive layer that attaches the substrate and the IC chip. Then, the adhesive layer would fail to properly fix the compressed form of the conductive balls, allowing the conductive balls to be restored in their form to increase the contact resistance between the conductive balls and the pad and the contact resistance between the conductive balls and the terminal.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form prior art that is already known in this country to a person of ordinary skill in the art.